Correction to: Response Surface Analysis of the Corrosion Effect of Metakaolin in Reinforced Concrete

Silicon - The original version of the article unfortunately contained an error.     

Response Surface Analysis of the Corrosion Effect of Metakaolin in Reinforced Concrete

Silicon - Concrete is one of the most utilized construction materials. The use of sustainable cementitious material is one of the new trends in concrete technology. Several cementitious materials...     

Propagation of Surfactant-Dispersed Multiwalled Carbon Nanotubes in Porous Media

Understanding the transport of carbon nanotubes in porous media is essential to their applications in subsurface reservoirs, e.g., delivering catalysts or chemicals to targeted formations. In this study, a series of laboratory experiments are conducted to explore the transport of surfactant-dispersed multiwalled nanotubes (MWNT) in different porous media in flow-through columns at elevated electrolyte levels. Noncovalent bonding of ethoxylated alcohols adsorbed on the MWNT surface provides them with outstanding dispersion stability and excellent transport properties in a crushed-limestone sand pack. Superior transport performance in silica sand is obtained with binary nonionic–anionic surfactant formulations, which provide both steric repulsion and electrostatic repulsion between nanoparticle–nanoparticle and nanoparticle–sand surface. The mobility of MWNT suspensions are further investigated in the exposure to multiphase flow, e.g., with residual oil present, or coinjected with air into the sand pack. Coinjecting surfactant-dispersed MWNT suspensions with air (i.e., MWNT-stabilized foams) has hardly any impact on their propagation; retention in the sand pack remains quite low. With the presence of oil in the sand pack, the transport of MWNT suspensions is highly dependent on the type of surfactants used as the dispersant. For surfactants that achieved modest interfacial tension (IFT) reduction, the injected MWNT suspension bypasses the oil phase, and little impact on retention is observed. When the dispersant surfactant is also adjusted for an ultralow IFT condition, greater MWNT retention in the porous medium is observed because surfactants detach from the MWNT surface and aggressively partition to the oil/water interface, allowing the MWNT to flocculate and become deposited in the porous medium.     

基于STC89C52RC的超声波测距系统设计

本文介绍了一种基于STC89C52RC的超声波测距系统的工作原理及其硬件组成和相应的软件流程。硬件系统由脉冲发射电路、接收电路、温度补偿电路和相应的控制电路组成。软件部分采用单片机C语言程序编程,主要由键盘扫描、定时器/计数器初始化、超声波发射子程序、中断服务子程序和LED动态显示子程序构成。同时,为了提高超声波测距精度,采用温度传感器进行环境温度检测,对超声波的传播速度进行校正。实测证明,系统具有较高的测量精度和较强的适应性。     

硝酸银显色法检测混凝土中氯离子的迁移

实验室和工程现场经常用硝酸银显色法检测混凝土中氯离子的迁移.有3种硝酸银显色法,即AgNO3+K2CrO4法、AgNO3+荧光素法以及AgNO3法,其中AgNCh法使用最广泛,因为AgN03法测试结果和其他两种方法相似却比其他两种方法容易操作.硝酸银显色法测量的变色边界氯离子浓度在很大范围内变化,很多因素诸如混凝土碱度、硝酸银浓度、取样方法以及混凝土中氯离子分析方法等均会对变色边界氯离子浓度测试结果产生影响. 采用硝酸银显色法测试的自由氯离子渗透深度以及通过变色边界自由氯离子浓度计算的表观扩散系数可以简单、快速地评价混凝土抗氧离子渗透性.     

数控落地镗铣床在挖掘机超长臂机加工的应用

针对挖掘机超长臂的结构与机加工特点,深入探讨了使用数控落地镗铣床加工超长臂的工艺方案,具体阐述了加工工艺过程。在生产实践中证明数控落地镗铣床不仅能保证超长臂的机加工质量,还能提高生产效率。     

Wielding the Double-Edged Sword of Inflammation: Building Biomaterial-Based Strategies for Immunomodulation in Ischemic Stroke Treatment

Stroke is a leading cause of disability with no current treatment to regenerate lost brain tissue. Innovative preclinical and clinical trials have attempted to improve stroke recovery by promoting cell survival, downregulating astrogliosis and inflammation, and improving neurogenesis and angiogenesis; however, the complexity of stroke pathophysiology raises many challenges. Previous attempts to grossly inhibit the inflammatory reaction failed to improve stroke outcomes, prompting scientists to explore selective modulation rather than unbiased inhibition. Although experimental studies involving immunomodulation are successful, strategies have largely failed in the clinic. Some of these approaches are hindered by poor delivery efficiency or cell survival, challenges that could be at least partially overcome using biomaterials. Biomaterials may enhance immunomodulatory processes by improving drug and cell delivery to the injured tissue. Furthermore, the materials themselves can support healing and may be designed to act as immunomodulators, thereby contributing to tissue regeneration and endogenous repair processes. Described here are novel biomaterial-based strategies to modulate the immune response after ischemic stroke, with an emphasis on extracellular matrix mimetics and hydrogels for local delivery of drugs and cells. Finally, a future perspective is described, highlighting the potential of these therapies to achieve clinical translation and improve patients’ functional repair.     

Variation of microstructure and mechanical property of slurry die cast Al-Si-Mg-Fe alloy

Semi-solid metal processing technologies have been intensively studied in recent years. Gas Induced Semi-Solid (GISS) is a slurry preparation technique for producing non-dendritic or globular structures for cast alloys. In the present study, GISS technique was used in conjunction with conventional die cast process for casting Al–Si–Mg–Fe alloy. The shape of die cast specimen was designed as a simple flat plate. The variation of microstructures and tensile properties of specimens from different locations of cast plates was studied. The results show that the specimens from bottom location, near the gate section and the middle location of cast plates are stronger and more ductility than those from the top location. The microstructural examination reveals that the specimens from top location of cast plates contain more defects, such as shrinkage pores than those from the other locations. These defects are resulted in lower strength and ductility of the cast product.     

A decision-making support system module for project manager selection according to past performance

This paper proposes a decision-making support system (DMSS) module for selecting project managers and demonstrates its implementation. The selection of a new project manager is based mainly on the past performance of potential managers, for example, on the relative performance evaluations they have received on projects managed by them in the past. Past projects are ranked in accordance with a ranking method. Project managers are ordered according to past project rank. The difference in quality between the past performance of the candidates is statistically examined using the Mann–Whitney–Wilcoxon U test. This enables the establishment of a subgroup of one or more preferred candidates, where the significance level of the statistical test has an impact on the subgroup size. The final candidate may be selected from this subgroup according to personal qualifications and suitability for the specific project. We demonstrated the use of such a DMSS module by an Israeli information technology company as part of their process to select a project manager. A ranking method within the Data Envelopment Analysis context (the Cross-Efficient method) was implemented with three inputs and four outputs selected for the project ranking.